Orbital bayonet saw

ABSTRACT

A bayonet-type saw having adjustable motor speed and orbital blade motion controls. A baffled passageway for directing air at the cutting zone is provided. An improved blade guide structure having a neck portion and two parallel spaced apart arms with a main roller bearing therebetween and saw blade side supporting nip rollers is included.

TECHNICAL FIELD

The present invention relates to power saws such as reciprocating saws,sometimes known as jig saws or saber saws. The present invention relatesmore particularly to hand-held power saws having an orbital blademotion.

BACKGROUND

Many types of power-operated hand tools such as saber saws or jig sawsare available. Many of these bayonet-type saws are capable of producingan orbital blade motion. Such a motion has a rectilinear component of agenerally up and down nature, and a fore and aft motion advancing thecutting blade into the workpiece. Typically the blade advances on thecutting stroke, which conventionally is the upstroke on most saws.

One of the principal advantages of the bayonet type saw over circularsaws and hand-operated band-type saws is the ability of the bayonet sawto make a curved cut along a relatively short radius.

Some bayonet-type saws have orbital motions which can be varied by theoperator. Typically, when performing tight scrolling cuts, a rectilinearblade motion has been required. Performing small radius cuts exerts atwisting action on the cutting blade which can make control of thecutting path difficult. In many cases, this lack of control has resultedfrom the blade guide portion of the bayonet saw being incapable ofadequately supporting and guiding the cutting blade.

Heretofore, bayonet-type saws have typically included a blade guidewhich has a roller wheel mounted for rotation along an axis generallyparallel to the work surface and perpendicular to the up and downrectilinear blade motion. Such a blade guide supports only the back sideof the cutting blade. During scroll cutting, the lack of lateral supportof the cutting blade has proven disadvantageous.

A modified version of the above-described blade guide includes a notchedor grooved roller bearing supporting the cutting blade. Such a bearinghas a blade receiving groove or slot within the blade engaging surface.The blade rests in the slot and therefore is supported along its backside, and along the rear most portion of the sides of the blade, for thedepth of the groove or slot. A grooved blade guide roller will typicallyprevent the back portion of the blade from moving laterally across theroller surface, but is of limited assistance in stabilizing the bladeagainst twisting action encountered during scroll cutting. Attempting tomake tight radial cuts with even this type of device can lead to a lackof control. The addition of an orbital motion to the blade, whichnormally speeds cutting of soft material such as wood, furtheraggravates the problem.

Consequently, currently available bayonet-type saws have required thatscroll cutting be performed at an operating speed below the operator'sability because of the physical limitations of the tool.

The present invention provides an improved bayonet-type saw having avariable orbital blade motion. The saw includes a blade guide having amain rotating bearing, for engaging the back side of a cutting blade,and a pair of nip roller bearings for engaging the sides of the cuttingblade. The saw also provides electronic speed control of the blademotion, and further includes a structure for selectively blowing airtoward the cutting region for removing debris and saw dust to improveoperator visibility of the cutting blade. Improved operator control andproductivity are achieved. Scroll cutting, even with moderate orbitalmotion, and increased speed are possible.

SUMMARY OF THE INVENTION

The invention is an orbital bayonet-type saw having a motor enclosedwithin a housing. A drive mechanism for driving the saw blade in an upand down motion is enclosed within the housing. The drive means includesan output shaft on a motor, and an assembly gear turned by the outputshaft. The assembly gear is itself rotatably mounted on a stationaryassembly gear shaft which also supports a gear crank hub (which carriesan oscillating counterweight), an orbit cam, and a crank with an offsetshaft, all of which rotate with the assembly gear. The offset shaft orcrank pin is affixed to the crank on the end of the assembly gear shaftopposite the assembly gear, with the orbit cam and gear crank hubtherebetween. An elongated saw blade holder engages the offset shaft andis slideably mounted for vertical movement within a blade holder bearingwithin the housing. The other end of the blade holder arm includes asawblade chuck.

The present invention further includes an orbit causing mechanismincluding an elongated orbit cam lever pivotally affixed at one endwithin the housing, with a cam following face at the opposite end. A camlever lobe is located between the ends of the cam lever, and the orbitcam following face is positioned against the orbit cam on the assemblygear shaft. A spring holds the cam following face against the orbit camduring operation.

A saw blade guide is pivotally affixed to the housing. The saw bladeguide has an extended neck passing through the housing and into positionto oscillatingly contact the orbit cam lever lobe. The orbit cam leverlobe moves in an arc as the lever arm pivots and the cam following faceengages the rotating orbit cam. The oscillating arc motion of the camlever lobe produces an oscillating motion in the neck of the saw bladeguide.

The saw blade guide further includes a pair of parallel arms, eachaffixed to the neck opposite the end of the neck which engages the camlever lobe. The arms are parallel to each other in spaced relation. Eacharm ends in a flange which lies perpendicular to the work surface andperpendicular to the straight ahead line of cut. The flanges eachinclude a sawblade side supporting nip roller, and a main rotatingbearing is located between the arms.

The invention includes a mechanism for varying the position of the pivotpoint of the orbit cam lever to control the amount of oscillation of theblade guide neck thus moving the saw blade guide and selectivelycontrolling the orbital path of the associated saw blade.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of the preferred embodiment of the presentinvention.

FIG. 2 is a partial side elevational view of the embodiment in FIG. 1,with portions shown in cross-section and the mechanism in a firstposition.

FIG. 3 is another partial elevational view similar to FIG. 1, butshowing the mechanism in a second position.

FIG. 4 is a front side sectional view taken generally along line 4--4 inFIG. 2.

FIG. 5 is a similar sectional view taken generally along line 5--5 inFIG. 2.

FIG. 6 is another similar sectional view taken generally along line 6--6in FIG. 2.

FIG. 7 is yet another similar sectional view taken generally along line7--7 in FIG. 3.

FIG. 8 is a fragmentary sectional view taken generally along line 8--8in FIG. 4 on an enlarged scale with portions broken away.

FIG. 9 is a partial fragmentary elevational view taken generally alongline 9--9 in FIG. 2, on a similar scale.

FIG. 10 is a partial elevational view, with portions shown incross-section, taken generally along 10--10 in FIG. 9 on a similarscale.

FIG. 11 is a partial perspective view on an enlarged scale, partiallyshowing the blade guide.

FIG. 12 is an exploded perspective view showing the component parts ofthe blade guide subassembly on a further enlarged scale.

FIG. 13 is a partial sectional plan view taken along line 13--13 of FIG.4 on an enlarged scale.

DETAILED DESCRIPTION OF THE INVENTION

Throughout the following description, reference will be made to thedrawings. The same reference numerals will be used throughout theseveral views to indicate the same or like parts of the invention.

Referring now to FIG. 1, the bayonet saw 10 includes a housing 20, asupporting base 21, and a saw blade 30 lying generally outside of thehousing 20. The saw blade 30 is supported and rides partially within ablade guide 40, and through a slot 23 in the base 21. The base 21supports the housing 20 so saw 30 is at a desired orientation to a workpiece being sawed.

In reference now to FIG. 2, the driving mechanism for the saw includes amotor 12 with an output shaft 14. The output shaft has mounted thereonan impeller or rotor 16 which exhausts heat from the motor 12 andprovides a source of air for removing shavings, debris, and saw dustfrom the cutting zone, as will be described later. The output shaft 14has geared teeth 18 on its outward end and is supported by a bearing 22.The teeth 18 on the output shaft 14 engage an assembly gear 24 whichrotates about its center on needle bearings 25 on a stationary assemblygear shaft 26. The assembly gear shaft also includes an orbit cam 28adjacent to the assembly gear. A counterweight 32 is provided forgenerally up and down motion on a gear crank hub 34 on the assembly gearshaft 26 outboard of the orbit cam 28.

The gear crank hub 34 is rotatably affixed on the assembly gear shaft 26with bearings 25 therebetween. A crank 42 is mounted on the gear crankhub 34 and includes a crank pin or offset shaft 36 which orbits thestationary assembly gear shaft 26. The offset shaft has an inboard endreceived within the crank 42 and an outboard end which is receivedwithin an oval slot 44 formed at one end of a blade holder arm 46.

The blade holder arm or carrier 46 is slideably received within a bladeholder bearing 48 supported by the housing 20. The blade holder arm orcarrier makes a generally rectilinear up and down motion duringoperation. The rotational motion of the motor is transmitted through ageared reduction to a rotational motion of the assembly gear 24 and theassociated orbit cam, gear crank hub, and crank. The oval slot 44 withinthe blade holder arm 46 converts the vertical component of the circularoffset shaft motion into up and down rectilinear motion. The horizontalcomponent of the circular offset shaft motion is expended as the offsetshaft moves horizontally in the oval opening of the blade holder arm 46.A blade grasping chuck 38 is affixed to the end of the blade holder 46outside of the housing 20.

The invention also includes an orbit causing mechanism. In reference nowspecifically to FIGS. 6 and 7, the orbit causing mechanism includes theorbit cam 28 and an orbit cam lever 52. The orbit cam lever 52 ispivotally affixed at one end at a point 54 within the housing. The orbitcam lever has a cam following face 56 at the opposite end, with a camlever lobe 58 therebetween. A spring 60 hooks beneath the orbit camlever and forces the cam following face 56 to press against the orbitcam 28.

The pivot point 54 of the cam lever is movable about an arc shaped path.The cam lever arm pivots on a pivot pin 64 offset from the center of anorbit control shaft 66 including an orbit control knob 68 (see FIG. 3).Rotation of the orbit control knob 68 and shaft 66 moves the pivot pin64 about approximately 180 degrees of arc. This movement of the pivotpin changes the pivot point 54 of the orbit cam lever 52 from a firstposition, wherein no orbital motion is imparted to the saw blade 30, toa second position where a substantial orbital motion is imparted to thesaw blade.

Orbital motion of the saw blade, or motion for and aft in the directionof the saw blade cutting path, is caused by the action of the saw bladeguide 40. As perhaps best seen in FIGS. 11 and 12, the saw blade guide40 has an extended neck member 72 which passes through the housing 20and contacts the orbit cam lever lobe 58. The blade guide includes apair of parallel arms 74, affixed to the neck 72 opposite the point ofengagement of the neck with the orbit cam lever lobe 58. The arms 74 areparallel and spaced from each other. Each arm terminates in a flange 76.The two flanges are coplanar and each includes a saw blade sidesupporting nip roller 78. The nip rollers are affixed to the flanges 76in rotating fashion by screws 106 or the like. The nip rollers do notcontact each other as is conventional in a nip roller, but rather arespaced apart substantially the width of a saw blade.

A main rotating bearing 82 is positioned between the arms 74 of the sawblade guide 40 on an axle pin 84 received by colinear orifices 86between the arms 74 of the saw blade guide 40. The main bearing 82 liesgenerally in the plane of the saw blade motion. Each arm includes avertically extending upper arm portion 88 and a horizontally extendinglower arm portion 92.

The blade guide 40 is affixed to the housing in pivoting relation by apivot pin 94 extending through the parallel arms 74 and received bycolinear orifices 96 in the arms and extending into the colinearorifices 98 within the body or housing 20. The main roller bearing 82can be centrally positioned on the axle pin 84 between a pair ofbushings 99. The pivot pin 94 may be retained in position by a pair ofC-clips 102. The axle pin 84 may be threaded and engage a nut 104 forholding the main bearing 82 in position (see FIG. 12). Alternately, oneof the parallel arms may be threaded to engage the axle pin 84.

The bearing 82 and the nip rollers 78 may comprise roller bearings (seeFIG. 8) which includes a hardened outer race or running surface. The niproller bearings 78 may be affixed to the flanges 76 of the blade guideby screws 106 (see FIG. 12), rivets or other suitable means. A chipdeflecting shield 79 partially encompasses the saw blade guide 40 andchuck 38.

In reference now to FIGS. 9 and 10, the orbit control mechanism,including the orbit control knob 68 is shown. The knob includes a rollerbearing detent system. The detent system includes a ball 112 urgedagainst a ball sized detent 114 on the inside surface of the knob 68 bya spring 116 within a hole 118 in the housing 20. The mechanism allowsthe orbit control knob and the orbit control pin 64 affixed thereto tobe selectively positioned in one of a number of locations. The knob 68has a number of detents 114 (see FIG. 9) each of which serves to holdthe knob in a given position. Four detents are shown. They have beenlabeled for operator identification with markings (0) through (3). Thedetents are spaced over a range of approximately 180 degrees of arc, andthe motion of the knob 66 is limited to this range by a block 122 andtwo stops 124.

At the end of the orbit control shaft 66 opposite the orbit control knob68 lies an orbit lever pivot pin 64 offset from the axis of rotation ofthe orbit control shaft 66. The orbit lever pivot pin engages the orbitcam lever 52 and serves as the pivot point 54 thereof. The orbit camlever may be retained on the orbit lever pivot pin by a C-ring 126 orthe like. Rotation of the orbit control knob moves the pivot point ofthe orbit cam lever about an arc. The pivot point of the orbit controllever can be positioned in a first position (the zero position shown onthe orbit control knob) wherein no oscillation of the blade guide neckis caused by the orbit cam lever. Rotation of the orbit control knob 180degrees (to the "3" position shown on the orbit control knob) results ina second position wherein a substantial (maximum) oscillation of theblade guide neck is caused by the orbit cam lever. A plurality ofintermediate positions between the first position (0) and the secondposition (3) are possible. These positions of the knob produceintermediate orbital blade motions. For operator convenience, two ofthese positions are indicated as (1) and (2) on the orbit control knob.More positions are possible, and the tool can be operated with the knobbetween detents.

In reference now to FIG. 3, the blower control feature is shown. Thisfeature comprises an inner air shaft 132 operatively connected to thecooling air impeller 16 affixed to the output shaft 14 of the motor 12.Cooling air drawn over the motor by the impeller is expelled from thehousing 20 through four exit passageways. Three of these passageways,collectively numbered 134, pass radially outwardly through the oppositesides of the housing. The fourth passageway or airshaft 132 passesdownwardly generally toward the area where the saw blade 30 isgenerating saw dust while in use. This passageway 132 includes amoveable baffle plate 136 which can be positioned in an open position(see FIG. 3) wherein air flow passes unobstructed toward the area ofcutting. This airflow is useful for blowing away sawdust, debris andcuttings. This greatly aids the visibility of the operator, particularlywhen attempting to cut along a line or other mark. The baffle can bemoved to completely obstruct the passageway 132 (dotted line in FIG. 3),in which case all of the cooling air exits through the three sideopenings 134. This position is useful when using the invention inconjunction with cutting metals or other materials which might requirethe use of a lubricant for the cutting blade. An exhaust directed towardthe cutting area might remove the cutting lubricant in a disadvantageousmanner. The baffle plate 136 is mounted for rotation about a baffleshaft 138 including a baffle control knob 140 outside the housing 20.

Further constructional details of the invention include a transversecounterweight lower guide pin 142 located within the housing forreceiving a slot 144 within the bottom portion of the counterweight 32and a pair of transverse upper guide pins 146. This mechanism retainsthe counterweight so that it performs an oscillating motion in a nearlyrectilinear fashion. The counterweight is further controlled by a pairof slider guide bearing pins 148 held between lugs 150 located withinthe housing 20 adjacent the location of the counterweight (see FIGS. 4and 13). The slider guide bearing pins 148 may be of circularcross-section, and the lugs 150 may be positioned other than as shown toretain the pins 148.

The blade holder bearing block 48 is mounted within the housing 20 andincludes a blade holder bearing gasket 152 between the bearing block andthe housing. The bearing is biased to maintain the blade holder in agenerally perpendicular position by a bearing spring 154. A blade guidegasket 156 is positioned between the blade guide neck 72 and the housing20. These gaskets help prevent the entry of debris and foreign matterinto the housing. The bearing block can pivot against the force of thebearing spring 154, on a bearing block pin 158. This pivoting actionaccommodates the motion of the blade holder during orbital saw blademotion.

OPERATION

The operator will select and install an appropriate saw blade for use incutting the desired work material. The operator can then select adesired blade speed by presetting an electronic control (not shown). Anorbit path is then selected and the operator positions the orbit controlknob 68 in the appropriate position. Turning on the motor by aconventional trigger or slide switch 160 then produces a rotationalmotion in the output shaft and associated assembly gear. This produces arotation of the assembly gear, orbit cam, gear crank hub and crank. Anoscillating motion of the counterweight and an orbiting motion of thecrank pin follow. The crank pin produces a generally rectilinear up anddown motion of the blade holder.

The blade holder moves in slideable fashion within the blade holderbearing block. The bearing block is spring-loaded to keep the bladeholder in a generally vertical orientation. The blade holder block canpivot on the bearing block pin to accommodate orbital blade motion. Anup and down motion is then transmitted to the saw blade through theblade holder arm and blade grasping chuck.

Orbital motion of the saw blade is produced by the action of the orbitcam on the cam following face of the orbit cam lever. The orbit camlever pivots about its pivot point attached to the orbit control knoband shaft. When the orbit control knob is positioned to produce orbitalmotion of the blade, the orbit cam lever lobe deflects the neck portionof the blade guide. This deflection of the neck portion of the bladeguide causes the blade guide to pivot about its pivot pin forcing theparallel arms of the blade guide and the associated main bearing to movein a fore and aft direction. This motion carries the saw blade with themain bearing and nip roller bearings. The forward thrust of the mainroller bearing takes place generally during the up stroke of the bladeholder. The forward thrust is caused by a downward action of the camlever lobe against the neck portion of the blade guide. As the orbit camrotates, the cam lever lobe moves in an upward direction returning theblade guide to its normal position. This return action generally takesplace on the downward (noncutting) stroke of the blade holder andassociated blade.

Adjustment in motor speed, blade orbit, and blower volume can be made bythe operator at any time. Adjustments to these controls can even be madeduring use of the device. By making appropriate adjustments in the motorspeed, orbit path and blower volume, the operator can achieve maximumproductivity. The blade guide structure allows improved stability andcontrol during scroll-type cuts and the speed control and orbit controlmechanisms allow optimal blade path and speed to be selected. Thebaffled passageway allows improved visibility when the operator isfollowing a mark or cutting line, yet allows the volume of air directedtoward the cutting zone to be eliminated if desired.

A number of characteristics and advantages of the invention have beenset forth above, together with the structure and operation of thepreferred embodiment of the orbital bayonet saw. The novel featuresthereof are pointed out in the following claims. The above disclosure ismerely illustrative, and changes may be made in detail with respect tothe size, shape, choice of materials and structural arrangement of thedevice within the principles of the invention to the full extentintended by the broad general meaning of the following claims.

What is claimed is:
 1. A blade guide for a bayonet type saw including ahousing, a motor within said housing, a driving means connected to themotor for producing an up and down motion in a saw blade connected tothe driving means and an orbit producing means for causing said blade toorbit in a plane including said up and down blade motion;said orbitproducing means including a reciprocating lever member operativelyconnected to said motor and a blade guide which engages said lever andsaid blade, said blade guide comprising:a neck member positioned withinsaid body to engage said lever; first and second parallel armsperpendicularly extending from said neck and each terminating in aflange, said flange on said first arm coplanar with said flange on saidsecond arm and said plane of said flanges perpendicular to said neck andperpendicular to said arms; a main rotating bearing positioned betweensaid arms in the plane of said saw blade motion and engaging the backsurface of said saw blade; and, a pair of nip roller bearings affixed tosaid flanges and forming a nip substantially the width of a saw blade,said nip rollers engaging the opposite sides of said saw blade.
 2. Theblade guide of claim 1 further comprising a pivot pin extending throughsaid parallel arms and received by colinear orifices within saidhousing.
 3. The blade guide of claim 1 further comprising a pair ofbushings and an axle pin for affixing said main bearing in a centralposition between said arms.
 4. The blade guide of claim 3 wherein saidparallel arms each include a vertically extending upper arm portion anda horizontally extending lower arm portion.
 5. The blade guide of claim4 wherein said axle pin spans said lower arm portions and is received bycolinear orifices within said lower arm portions.
 6. An orbital jig sawhaving a housing, a motor within said housing, a motor driven reciprocalsaw blade carrier with a saw blade, and orbital drive means, saidorbital drive means comprising:a pivoting cam following yoke memberconnected to a cam on said motor and a movable blade guide affixed tosaid housing in deflecting relation between said lever and said sawblade, said lever deflecting said blade guide on movement of said cam;said saw blade guide having an extended neck member passing through saidhousing and engaging said lever; a pair of parallel arms, each affixedto said neck opposite said abutment with said yoke, said arms parallelto each other in spaced relation and terminating in coplanar flanges,each of said flanges including a saw blade side supporting nip rollerrotatably affixed thereto, said arms receiving a main rotating bearingtherebetween, said main bearing positioned to lie in contact with theback side of said saw blade; and, means for variably positioning thepivot point of said pivoting lever to selectively control saiddeflection of said neck member, from a first position wherein nodeflection of said neck is caused by said yoke, to a second positionwherein a substantial deflection of said neck is caused by said yoke. 7.The device of claim 6 wherein said deflection of said neck memberproduces an orbital motion of said saw blade.
 8. The device of claim 6wherein means for variably positioning said pivot point includes aplurality of intermediate positions between said first position and saidsecond position.
 9. The device of claim 6 further comprising a pivot pinextending through said parallel arms and received by colinear orificeswithin said housing.
 10. The device of claim 6 further comprising a pairof bushings and an axle pin for affixing said main bearing in a centralposition between said arms.
 11. An orbital saw comprising:a motor; ahousing surrounding said motor; a drive means for driving a saw bladeexternal of said housing in an up and down motion, said drive meansincluding an output shaft on said motor, an assembly gear, engaging saidoutput shaft and rotatably mounted on an assembly gear shaft, a counterweight rotatably affixed on said assembly gear shaft, an orbit camrotatably affixed on said assembly gear shaft between said assembly gearand said counter weight, and an offset shaft affixed to and orbitingsaid assembly gear shaft; an elongated saw blade holder arm mounted forsubstantially vertical movement within said housing and including anoval slot at one end, said slot receiving said offset shaft, and a sawblade chuck at the opposite end of said arm; an orbit causing means forcausing an orbital blade motion including an elongated orbit cam leverpivotally affixed at one end at a point within said housing and having acam following face at the opposite end and a cam lever lobetherebetween, said orbit cam following face positioned against saidorbit cam, a biasing means for holding said cam following face againstsaid orbit cam; a saw blade guide having an extended neck member passingthrough said housing and oscillatingly contacting said orbit cam leverlobe; a pair of parallel arms, each affixed to said neck opposite saidengagement with said orbit cam lever, said arms parallel to each otherin spaced relation and terminating in coplanar flanges, each of saidflanges including a saw blade side supporting nip roller rotatablyaffixed thereto, said arms receiving a main rotating bearingtherebetween, said main bearing contacting the back side of said sawblade; and, means for variably positioning the pivot point of said orbitcam lever to selectively control said oscillation of said neck member,from a first position wherein no oscillation of said neck is caused bysaid orbit cam lever, to a second position wherein a substantialoscillation of said neck is caused by said orbit cam lever.
 12. Thedevice of claim 11 wherein means for variably positioning said pivotpoint includes a plurality of intermediate positions between said firstposition and said second position.
 13. The device of claim 11 furthercomprising a pivot pin extending through said parallel saw blade guidearms and received by colinear orifices within said housing.
 14. Thedevice of claim 11 further comprising a pair of bushings and an axle pinfor affixing said main bearing in a central position between said sawblade guide arms.
 15. The device of claim 12, further comprising anorbit control shaft mounted for rotation with said housing and includingan orbit control knob affixed at one end thereto and an orbit leverpivot pin mounted on said orbit control shaft opposite said knob, saidorbit lever pivot pin mounted from the axis of rotation of said shaftand engaging said pivot point of said orbit cam lever to move said pivotpoint of said orbit cam lever in an arc.
 16. The device of claim 12further comprising an orbit control shaft mounted for rotation with saidhousing and including an orbit control knob affixed at one end theretoand an orbit lever pivot pin mounted on said orbit control shaftopposite said knob, said orbit lever pivot pin mounted from the axis ofrotation of said shaft and engaging said pivot point of said orbit camlever to move said pivot point of said orbit cam lever in an arc.